We propose to study the anaerobic protein genes in maize, a group of twenty genes whose expression is induced by anaerobic stress. Our studies will be primarily concerned with one of these genes, alcohol dehydrogenase 1 (Adh1). The existence of well-characterized mutant alleles and naturally occurring variants of Adh1 which exhibit altered quantitative and organ-specific regulatory behavior provide this system with exciting possibilities in the investigation of eucaryotic gene regulation. We will use recombinant DNA technology to purify genomic DNA fragments containing normal and mutant alleles of Adh1. We will determine the nature of the mutational changes in the Adhl alleles which result in altered regulatory behavior. We will use molecularly cloned DNA probes complementary to ADH1-mRNA to measure the accumulation of ADH1-mRNA and its precursors during anaerobic stress. By comparing mutant alleles with their "normal" progenitor alleles we will determine which process leading to the production of translatable ADH1-mRNA is altered in each mutant. From the correlation of altered structure with altered function we will be able to define regions of specific regulatory function at the Adh1 gene. We will also investigate the roles of DNA methylation and chromatin structure in differential gene expression. The availability of Adh1 alleles and variants with different quantitative and organ-specific levels of expression should provide new kinds of information about the roles of DNA methylation and chromatin structure.